For example, in the first or last sedimentation pool of sewage a treatment plant, it is designed to sediment sludge in the bottom of the pool, and scrape it in one direction of the pool, and discharge the sludge out of the pool. The design is the same in a tap water treating plant.
As one method of sludge scraping, the flight circulation chain driving system is known.
This system comprises a plurality of rotary shafts rotatably mounted with the axial center directed in the width direction of the pool, sprockets mounted on each rotary shaft by two pieces each set apart, and right and left chains applied through these sprockets. At the outer side of the chains, a plurality of flights (scraping plates) are provided at specific intervals in the circulation direction, and as these flights move along on the guide rails provided in the bottom of the pool, the flights scrape and collect the sludge in the bottom of the pool in one direction, and bring the sludge to the sludge pit. The sludge is pumped out of the pit and discharged out of the pool.
This chain driving system is large and complicated in structure, expensive, and difficult to install, and it is high in maintenance cost because of circulatory motion, and is inferior in economy.
On the other hand, instead of the chain circulation system, the system of moving along the bottom of the pool linearly and reciprocatively is known. The system comprises a longitudinal guide (guide rail) provided in the bottom of the pool, a work member for moving along the guide, drive means (rope or the like) for moving the work member reciprocatively, and a scraping member attached to the work member, and it is designed to scrape and collect the sludge settling in the bottom of the treatment pool in one direction by the motion of the scraping member, and discharge out of the pool.
It has the following defects.
In addition to guides and their mounting devices, two guides, right and left, are provided apart from each other in the width direction of the pool, which require a large work member straddling widely between the guides. Accordingly, the structure was very large and complicated, and it was expensive and difficult in installation, and still more the maintenance control cost was high for keeping circular motions and it was not economical.
It is hence a primary object of the invention to present an apparatus which is simple in the entire structure and easy to install, and inexpensive on the whole.